Field of the Invention
Aspects of the present invention generally relate to power supply control over an information processing apparatus.
Description of the Related Art
Recent information processing apparatuses have a great number of functional units mounted thereon, such as units for wired and wireless network functions, a plurality of storage functions, and a graphic accelerator function. Allowing such a great number of functional units to operate would increase power consumption. Therefore, information processing apparatuses would have a power supply unit with such a large rated output capacity as to be able to cope with large power consumption. Furthermore, it is generally known that a power supply unit would increase in size and become expensive as the rated output capacity thereof is made larger.
Japanese Patent Application Laid-Open No. 4-109457 discusses a technique to sequentially activate a plurality of functional units (including, for example, a disk drive) at intervals of a predetermined time, without simultaneously activating the plurality of functional units, for the purpose of lowering power consumption.
However, the time required from when a certain functional unit (a disk drive) starts to be activated until when the power consumption lowers after the passage of the time of high power consumption varies widely depending on functional units. Therefore, to prevent times of high power consumption of a plurality of functional units from overlapping each other, a next functional unit is started to activate after the lapse of a somewhat long time. As a result, the time required until an information processing apparatus is completely started up may disadvantageously become longer.
Taking a 3.5-inch hard disk drive as an example of a functional unit, since the time during which the power consumption thereof is high is several seconds to a dozen of seconds, a next functional unit is started to activate after the lapse of about 20 seconds. Therefore, the time required until an information processing apparatus is completely started up may become longer. This issue is not limited to activation of a hard disk drive, but a similar issue also occurs in activation of various functional units.